From d7cf771072b3153e7641a9cef61160974cee8a39 Mon Sep 17 00:00:00 2001
From: jBarz <jbarboza@ca.ibm.com>
Date: Fri, 27 Jan 2017 09:49:41 -0500
Subject: [PATCH] unix: use union to follow strict aliasing rules
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With strict-aliasing rules, a char* type can be cast to any other
pointer type. However, that does not necessarily mean char array
type. So instead of de-referencing a char array, use a union with an
additional char member for aliasing.

PR-URL: https://github.com/libuv/libuv/pull/1211
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>
---
 src/unix/stream.c |  9 +++++++--
 src/unix/udp.c    | 12 ++++++++----
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/unix/stream.c b/src/unix/stream.c
index 7059df16..dbd04f2b 100644
--- a/src/unix/stream.c
+++ b/src/unix/stream.c
@@ -785,7 +785,12 @@ start:
     struct msghdr msg;
     struct cmsghdr *cmsg;
     int fd_to_send = uv__handle_fd((uv_handle_t*) req->send_handle);
-    char scratch[64] = {0};
+    union {
+      char data[64];
+      struct cmsghdr alias;
+    } scratch;
+
+    memset(&scratch, 0, sizeof(scratch));
 
     assert(fd_to_send >= 0);
 
@@ -795,7 +800,7 @@ start:
     msg.msg_iovlen = iovcnt;
     msg.msg_flags = 0;
 
-    msg.msg_control = (void*) scratch;
+    msg.msg_control = &scratch.alias;
     msg.msg_controllen = CMSG_SPACE(sizeof(fd_to_send));
 
     cmsg = CMSG_FIRSTHDR(&msg);
diff --git a/src/unix/udp.c b/src/unix/udp.c
index 1cd49257..f9630c85 100644
--- a/src/unix/udp.c
+++ b/src/unix/udp.c
@@ -349,7 +349,11 @@ out:
 static int uv__udp_maybe_deferred_bind(uv_udp_t* handle,
                                        int domain,
                                        unsigned int flags) {
-  unsigned char taddr[sizeof(struct sockaddr_in6)];
+  union {
+    struct sockaddr_in6 in6;
+    struct sockaddr_in in;
+    struct sockaddr addr;
+  } taddr;
   socklen_t addrlen;
 
   if (handle->io_watcher.fd != -1)
@@ -358,7 +362,7 @@ static int uv__udp_maybe_deferred_bind(uv_udp_t* handle,
   switch (domain) {
   case AF_INET:
   {
-    struct sockaddr_in* addr = (void*)&taddr;
+    struct sockaddr_in* addr = &taddr.in;
     memset(addr, 0, sizeof *addr);
     addr->sin_family = AF_INET;
     addr->sin_addr.s_addr = INADDR_ANY;
@@ -367,7 +371,7 @@ static int uv__udp_maybe_deferred_bind(uv_udp_t* handle,
   }
   case AF_INET6:
   {
-    struct sockaddr_in6* addr = (void*)&taddr;
+    struct sockaddr_in6* addr = &taddr.in6;
     memset(addr, 0, sizeof *addr);
     addr->sin6_family = AF_INET6;
     addr->sin6_addr = in6addr_any;
@@ -379,7 +383,7 @@ static int uv__udp_maybe_deferred_bind(uv_udp_t* handle,
     abort();
   }
 
-  return uv__udp_bind(handle, (const struct sockaddr*) &taddr, addrlen, flags);
+  return uv__udp_bind(handle, &taddr.addr, addrlen, flags);
 }